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Articles by Vikyath Ram
Page 3 of 10
How can I create a MySQL view that takes the values from a table based on some condition(s)?
If we want to create a view that takes the values from a table based on some particular condition(s) then we have to use WHERE clause while creating the view. The values depending upon the WHERE clause will be stored in view. The syntax of creating a MySQL view with WHERE clause can be as follows −SyntaxCreate View view_name AS Select_statements FROM table WHERE condition(s);ExampleTo illustrate the above concept, we are using the following data from table ‘Student_info’ −mysql> Select * from student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 ...
Read MoreHow can we start MySQL event scheduler?
Actually, MySQL event scheduler is a process that runs in the background and constantly looks for the events to execute. But before we create or schedule an event we just have to start the scheduler. It can start with the help of the following statement −mysql> SET GLOBAL event_scheduler = ON; Query OK, 0 rows affected (0.07 sec)Now with the help of the following statement, we can check its status in MySQL process list −mysql> SHOW PROCESSLIST\G *************************** 1. row *************************** Id: 3 User: root Host: localhost:49500 db: query Command: Query Time: 0 State: ...
Read MoreHow to initialize and compare strings?
Following example compares two strings by using str compareTo (string), str compareToIgnoreCase(String) and str compareTo(object string) of string class and returns the ascii difference of first odd characters of compared strings.Example Live Demopublic class StringCompareEmp{ public static void main(String args[]) { String str = "Hello World"; String anotherString = "hello world"; Object objStr = str; System.out.println( str.compareTo(anotherString) ); System.out.println( str.compareToIgnoreCase(anotherString) ); System.out.println( str.compareTo(objStr.toString())); } }OutputThe above code sample will produce the following result.-32 0 0String compare by equals()This method compares ...
Read MoreWhat are single row and multiple row subqueries?
Single Row Sub QueryA single-row subquery is used when the outer query's results are based on a single, unknown value. Although this query type is formally called "single-row, " the name implies that the query returns multiple columns-but only one row of results. However, a single-row subquery can return only one row of results consisting of only one column to the outer query.In the below SELECT query, inner MySQL returns only one row i.e. the minimum salary for the company. It, in turn, uses this value to compare the salary of all the employees and displays only those, whose salary ...
Read MoreIn MySQL, how does the precedence of ! operator in comparison with NOT operator depends upon HIGH_NOT_PRECEDENCE SQL mode?
In MySQL, basically the precedence of ! operator in comparison with NOT operator depends upon the enabling or disabling of HIGH_NOT_PRECEDENCE SQL mode as follows −Disabled HIGH_NOT_PRECEDENCE SQL − In this case,! the operator has higher precedence than NOT operator.Enabled HIGH_NOT_PRECEDENCE SQL − In this case,! the operator has the same precedence as NOT operator.
Read MoreGenerating random numbers in Java
We can generate random numbers using three ways in Java.Using java.util.Random class − Object of Random class can be used to generate random numbers using nextInt(), nextDouble() etc. methods.Using java.lang.Math class − Math.random() methods returns a random double whenever invoked.Using java.util.concurrent.ThreadLocalRandom class − ThreadLocalRandom.current().nextInt() method and similar othjer methods return a random numbers whenever invoked.Exampleimport java.util.Random; import java.util.concurrent.ThreadLocalRandom; public class Tester { public static void main(String[] args) { generateUsingRandom(); generateUsingMathRandom(); generateUsingThreadLocalRandom(); } private static void generateUsingRandom() { Random random = new Random(); ...
Read MoreFlow control in a try catch finally in Java
A method catches an exception using a combination of the try and catch keywords. A try/catch block is placed around the code that might generate an exception. Code within a try/catch block is referred to as protected code, and the syntax for using try/catch looks like the following −Syntaxtry { // Protected code } catch (ExceptionName e1) { // Catch block }The code which is prone to exceptions is placed in the try block. When an exception occurs, that exception occurred is handled by catch block associated with it. Every try block should be immediately followed either by ...
Read Morefinal local variable in Java
Local VariableLocal variables are declared in methods, constructors, or blocks.Local variables are created when the method, constructor or block is entered and the variable will be destroyed once it exits the method, constructor, or block.Access modifiers cannot be used for local variables.Local variables are visible only within the declared method, constructor, or block.Local variables are implemented at stack level internally.There is no default value for local variables, so local variables should be declared and an initial value should be assigned before the first use.final Local Variablefinal is the only allowed access modifier for local variables.final local variable is not required ...
Read MoreFinal static variables in Java
Final Static VariablesClass variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block.There would only be one copy of each class variable per class, regardless of how many objects are created from it.Static variables are normally declared as constants using the final keyword. Constants are variables that are declared as public/private, final, and static. Constant variables never change from their initial value.Static variables are stored in the static memory, mostly declared as final and used as either public or private constants.Static variables are created when the program ...
Read MoreFind free disk space using Java
java.io.File class provides following useful methods to figure out the free disk space available.Sr.No.Method & Description1public long getFreeSpace()Returns the number of unallocated bytes in the partition named by this abstract path name.2public long getTotalSpace()Returns the size of the partition named by this abstract pathname.3public long getUsableSpace()Returns the number of bytes available to this virtual machine on the partition named by this abstract pathname.Following example showcases the use of above methods.Example Finalimport java.io.File; import java.text.NumberFormat; public class Tester { public static void main(String[] args) { NumberFormat numberFormat = NumberFormat.getInstance(); numberFormat.setMaximumFractionDigits(2); ...
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